On the introduction of radiological examinations in digital format, surgeons began to have problems during the manual preoperative planning. Thus, arises the need for these surgeons to resort to alternative methods for the preoperative surgeries planning in a virtual mode, especially using medical images from the patient.
The benefits of a computer-implemented method for surgery planning are high. There is currently a great interest in the development of digital medical imaging techniques.
Document U.S. Pat. No. 5,824,085 A discloses a method, a system and an apparatus for planning the position of a prosthesis within a bone, specifically, within a long bone such as the femur, tibia, humerus, ulna and radius, including specific procedures for the total hip and knee joint replacement, long bone osteotomy, and other similar ones.
This solution generates a bone model from a digital medical image of the bone. Then a prosthetic model is selected from a library of prosthetic templates. Subsequently, a cavity model is formed based on the design of the prosthesis and/or on the bone pattern. The cavity model may then be positioned on the bone model, interactively by the surgeon or automatically through a method based on clinical parameters, to determine a reasonable location for the implantation of the prosthesis in the bone.
This solution presents some problems, particularly in the realization of automatic positioning of the prosthesis if there are any problems with the positions taken by the patient when the medical image was made. Moreover, no more than 2D models are used, which in this case reduces the stereoscopic vision of the surgeon, and also the difficulty in understanding when there are problems in a different steering axis of what is presented. In addition to the problems presented, it may also be highlighted some drawbacks to the use of this solution, since it is only directed to long bones, specifically for two types of surgery. In order to use this technology, a particular CT scan must be taken to obtain the coordinate system for the robotic system.
The solution disclosed in US 2005/054917 A1 relates to a method implemented by a computer system for planning an orthopedic surgery. Among the many features of this solution: a) provides a digital library of representative models of orthopedic prostheses; b) shows the image of the patient, showing its relevant anatomical features for orthopedic surgery; c) calibrates the medical image of the patient; d) features on the medical image of the patient a geometrical construction defined by a plurality of interrelated geometric parameters; e) allows the surgeon to reconfigure the geometrical construction by adjusting the geometric parameters according to the anatomical features of the underlying patient medical image; f) allows the selection of at least one model from the library, according to the geometric parameters established by the surgeon.
This solution presents some problems and disadvantages, such as: not using the full potential of CT and MRI; the fact that only allows 2D sectional view in three different axes, precluding the sectional view in three different axes, disabling a stereoscopic vision; and if the X-ray is done without a marker, this medical image can no longer be used for the planning of orthopedic surgery. Thus, the solution is dependent on how the imaging study is performed.
Document US 2005/059873 A1 discloses a solution related to a method and an apparatus for the preoperative planning and simulation of orthopedic surgical procedures that use medical imaging. The preoperative planning includes the acquisition, calibration and medical image registration, as well as the reduction of the fracture or the selection of the prosthesis, the application of fixative elements and the creation of the planning report.
The described method is composed of: a) obtaining the medical image; b) segmenting the anatomical structure of the medical image, such as bone, but not limiting itself only to bone segments, and manipulating the image segments to simulate a desirable result of the orthopedic surgical procedure; c) marking segments of anatomical structures in medical images; d) the performance of different measurements and analysis, such as the difference in length, angle measurements, as well as sets of more complex measurements, such as deformity analysis, structural links in terms of distances and angles between each other; e) planning that comprises means for producing output images.
This solutions presents some problems and disadvantages, such as not using the full potential of CT scan and MRI images; the fact that it only permits the cutoff in three different viewing axes which does not allow a stereoscopic vision; the impossibility of combining the cutting in different axes does not allow a clear and accurate view of what the plan to be performed; and if this is done with an X-ray without marker, this medical image can no longer be used for the planning process of orthopedic surgery. Thus, the solution is dependent on how the imaging study was performed.
Document US 2012/221114 A1 exposes a solution that refers to a case for modular components of the neck for hip prostheses. It may include indicators based on independent variables associated with the physical characteristics of the prosthesis, including leg length, offset, and anteversion. During the surgery, the surgeon may be faced with the need to change a modular neck which was selected before surgery. Thus, the surgeon may want to change at least one of the variables, for example, the leg length, offset and/or the anteversion. This way the surgeon can select, quickly and easily, a different modular neck based on the evaluation of one of the variables, without the need to reevaluate the other variables. The method described here may comprise the preoperative planning, where a template including a coordinate system is used.
This solution presents some problems and drawbacks, such as: not using any computer system that is able to validate the process defined in the solution; does not provide the surgeon with a planning process, but with a resolution at the time of the surgery; the surgeon cannot, before the surgery, have a clear and accurate view of what awaits him at the time of the surgery. If there is the possibility of making changes within the surgery room, problems may arise due to the lack of planning, and an increase of time in which the patient is exposed to infections.
The method disclosed in document WO 2014/095853 A1 is related to the generation and manufacture of a surgical guide for steering a bone surgery, and surgical guides which can be obtained by the mentioned method. More particularly, methods are provided to generate a surgical guide to steer a surgical procedure in a first bone of a patient, comprising: a) the provision of a three-dimensional model of at least a portion of the first bone and of a second bone of the patient; b) determining or identifying a contact surface on the first bone; c) identification of a contact surface on the second bone; d) determining a range of motion between the second bone and the first bone, using at least one degree of freedom; e) generation of a surgical guide.
This solution does not allow interoperation of structurally different images. The solution is related to the implementation of methods to allow determining the surgical guides which allow the realization of safer surgeries, however, it does not become an effective planning tool.
Currently it is possible to use digital methods to make the planning of the surgeries, instead of the traditional acetates. However, existing solutions only allow surgeons to perform the preoperative planning in a 2D environment. Thus, these solutions present themselves insufficient, not allowing the surgeon to evaluate, clearly and precisely, which material to be used in surgery is more appropriate for the patient in question, since they often do not have a clear understanding of the extension of the injury.
With the use of a 2D environment, faults may arise in planning and consequently in surgery due to, for example, the inappropriate choice of prosthetic material. This can result in an increased time of surgery because the surgeon may have to wait for an alternative prosthetic material or may have to make additional incisions. In addition, improper choice of the prosthetic material will likely lead to post-operative complications. All these factors tend to increase costs, requiring extra time to assist the hospital staff and the patient, and also cause increased pain and inconvenience to the latter.
The technological solutions that are intended to assist the currently existing surgical planning, have been positively evolving. However, they still do not respond to all the needs faced by the surgeons during the surgical planning. These solutions have been insufficient because they do not allow the surgeon to sufficiently clearly assess the impact of the idealized approach.
In general, any of the above solutions has the following shortcomings:                does not allow a stereoscopic vision of the patient's lesion;        does not allow the handling and intersection of the various 3D models—the body structures of the patient and the digital representations of the prosthetic materials;        does not have the conjugation between 2D and 3D environments, updated in real time;        prevents building the model from the various body structures;        does not allow the segmentation of specific areas of the represented anatomical structures;        complex and less appealing processes which often leads to failures in planning and later in the surgery.        
In this sense, a solution that allows the surgeon to have a precise notion of what awaits him at the time of surgery is desirable.